1. Field of the Invention
The invention relates to a lighting apparatus, more particularly to a lighting apparatus with enhanced heat dissipation ability.
2. Description of the Related Art
Light-emitting diodes (LEDs) have advantages of high luminance, energy-saving, etc., and belong to solid-state illuminations. Thus, there is a growing trend for the LEDs to serve as lighting apparatuses. In the case of replacing a conventional lamp (such as a tungsten bulb) using a LED lighting apparatus, a sufficient number of the LEDs should be provided in the LED lighting apparatus to have luminance comparable to the conventional lamp. However, if the heat generated by the LEDs in the LED lighting apparatus is not dissipated efficiently, light degradation may occur due to overheating of the LEDs. As such, the LED lighting apparatus may have a shorter service life.
Accordingly, in order to provide a LED lighting apparatus with improved heat dissipation, the applicant of this invention proposed a LED bulb, as disclosed in U.S. Patent Application Publication No. 20110273072, in which a plurality of LEDs are mounted to a circuit board, and a heat sink is in close contact with the circuit board opposite to the LEDs. With the heat sink, the heat generated by the LEDs can be transferred outwardly through a screw base of the LED bulb.
However, the applicant of this invention found that the heat dissipation problem is likely to occur in a small volume LED bulb (such as one having an E17-type screw base), even if the small volume LED bulb is provided with the aforesaid heat sink. This is because in order to have sufficient luminance, the LEDs in the small volume bulb are arranged in a relatively high density. In addition, since the volume of space inside the LED bulb is relatively small, the heat-exchanging area for the heat sink may be insufficient so that the heat energy generated by the LEDs may not be efficiently transferred to the screw base of the LED bulb through the heat sink, thereby resulting in an increase in the temperature of the LEDs that may shorten the service life of the LED bulb.